Its now 5 years later and all I can say about my Whisper Express is:
In my 1380 hours of flying I have not find a better dual purpose plane, cheep to run, and very safe to fly, with or without engine.
Enough space for two 110kg pilots, huge luggage compartment. On one weekend away we load her up to 785kg MAUW (more than the legal weight) and she still climb at 500ft per min.
I did a few upgrades on the initial plane, most of it only cosmetic, also install a better looking Joystick, trims on the wings and ailerons.
There was no need for any other changes.
Attached a few photos of the last 5 years.